Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jul 03 2023 16:32:14 ACUS01 KWNS 031632 SWODY1 SPC AC 031630 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Jul 03 2023 Valid 031630Z - 041200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS NORTHWEST WY/WESTERN SD AND THE LOWER MID-ATLANTIC STATES... ....SUMMARY... A swath of severe wind gusts from 60-80 mph and isolated very large hail are probable across a portion of northeast Wyoming into western South Dakota this evening. Scattered damaging winds from strong to isolated severe gusts are likely across parts of the Lower Mid-Atlantic States through early evening. ....Lee of the Big Horns through SD... A shortwave trough over the northern Rockies will shift east and yield a strengthening mid-level speed max across eastern MT by this evening. Trailing portion of a cold front will become quasi-stationary across southern SD with post-frontal upslope flow expected over the Big Horns and Black Hills. A plume of enhanced low-level moisture near/north of the front in conjunction with steep mid-level lapse rates will support a corridor of MLCAPE from 1500-2500 J/kg. With weak low-level easterlies beneath the strengthening mid-level westerlies, hodographs should become quite elongated and nearly straight, yielding at least a few supercells with left/right-splits. Isolated very large hail is expected initially. The strong forcing for ascent and cold pool consolidation may result in a small MCS with potential for bowing structures centered on the western SD vicinity this evening. This would likely yield an increased severe wind threat of 60-80 mph gusts. Increasing MLCIN after sunset in conjunction with the narrowness of the buoyancy plume should yield a relatively confined swath/more isolated severe wind threat overnight into eastern SD. ....Mid-Atlantic States A slowly weakening mid-level trough over the Lower Great Lakes will gradually progress across the Northeast through tonight. Differential boundary-layer heating across a lee trough along the central to southern Appalachians will be the focus for scattered thunderstorms this afternoon. A belt of enhanced 35-45 kt west-southwesterlies was sampled at 2-5 km MSL in 12Z soundings across VA to the DE Valley. While this flow regime will slowly subside/shift east through the day, it will remain favorable for widely spaced multicell clusters that evolve into short-line segments spreading east towards the coast. Hodographs will be relatively straight and modestly elongated, especially with northern extent, but mid-level lapse rates will remain weak. This suggests severe hail will probably remain isolated, but even small hail should help to enhance water-loaded downdrafts. Multiple swaths of at least scattered damaging winds are likely through early evening. ....Deep South to OK... Remnants of a weakening cold front will serve as an effective surface trough/boundary-layer moisture gradient arcing west from the TN Valley to an MCV over western OK. Scattered thunderstorms are expected along this arc during the afternoon with moderately large buoyancy characterized by MLCAPE of 2000-3000 J/kg. Despite weak vertical shear, water-loaded downdrafts will support sporadic damaging winds through about dusk. ....MN vicinity... Scattered thunderstorms will develop along a cold front from northeast to southwest MN this afternoon. Deep-layer vertical shear will be rather weak, as the front remains displaced well east of stronger mid-level flow attendant to the SK/MB upper low. But large buoyancy with MLCAPE of 2500-3500 J/kg will support pulse to weakly congealing clusters along the front with primary threats of sporadic microbursts and hail. ....Central Rockies to northern Great Basin... Isolated to scattered high-based thunderstorm development is expected this afternoon. Inverted-V profiles with modest CAPE and large DCAPE, in combination with the southern periphery of 25-40 kt mid-level flow, will support the potential for at least isolated strong-severe outflow gusts of 55-70 mph. ...Grams/Supinie.. 07/03/2023 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .